Application of Dynamic Detailed Thermal Hydraulic Model on a Transformer With Zig-Zag Winding Scale Model

The paper presents the detailed dynamic thermal-hydraulic network model (THNM) for liquid-immersed power transformers (LIPT). Detailed static THNMs are prevalent in thermal design practice, but detailed dynamic THNM have not yet reached an adequate technology readiness level (TRL). Dynamic THNM describes local heat transfer and hydraulic phenomena in detail, integrating them into a global model of the complete transformer, which can be used for real-time applications. Consequently, a dynamic THNM provides a good foundation for creating a digital twin module of the transformer's transient thermal behavior during real grid operation. The paper explains the advanced detailed dynamic THNM and points out the differences from other existing approaches. It also describes the details of the model application to an experimental setup closely resembling a real transformer. The calculation results are compared with the experimental results and an error below 1.85 K in steady-state and 3.23 K after the first hour period from the cold start is observed for the discs’ temperature. This study also shows that the execution time is shorter than the real thermal transient process, which is a criterion required for real-time applications.